Our ANBOS had to become professional stone throwers. They could not safely take a step on the open grasslands without their armament of stones. One stone was not enough to ensure their safety; they needed a handful of stones.

But how can apes carry a handful of stones? On the open grasslands, plenty of animal hides could be found. Sabre toothed tigers ate the entrails of their kill. The hyenas with their mighty jaws were capable of eating the rest of the carcass, including bones, but left the basically inedible, hairy hides. So the ANBOS used those animal hides to carry things; and with their long experience in braiding their sleep nests, knitting these hides together was easy. But how would apes carry bags filled with stones? How do bonobos and chimps carry heavy things? They use their hands, and in order to do so they must walk upright on their feet.

In tens of hundreds of thousands of years our ANBOS, having no other choice, turned into ‘professional’ bipeds with longer and stronger legs, special pelvic and buttock muscles, special midriff, and adapted blood circulation. At least they began to develop these features in a way that was good enough for foraging on the savannah. They still kept the climbing facilities of their hands and feet: it was not safe to sleep on the ground, so they still had to make their sleeping platforms high in the bushland trees.

Females had to carry their babies and gather food for themselves and the rest of the group, so they couldn’t carry and throw stones. Males couldn’t gather food: they had to protect the others, because the predators were always watchful for moments of inattentiveness. So from the very beginning, our ANBOS cultivated a division of labour. Women and children gathered the food: grass seeds, tubers and roots (with digging sticks), larvae and insects, eggs and small animals. The adult men did nothing but provide safety. The groups with the most effective behavior flourished, kept more young alive and soon outnumbered the groups that were clumsy at these things. In tens of hundreds of thousands of years, through hundreds of generations, the most adept populations survived.

The same mechanism applies to group harmony. Bonobos live in female-dominated groups characterized by group harmony. They solve all tensions with sex. It is clear that our ANBOS ‘professionalised’ this behaviour too. Nice breasts and buttocks for the women (the ‘attractive’ red vaginas of the chimpanzee-women and heavy scrotums of the males were not maintainable for bipeds), large penises for the men, and continuous sexual willingness and unnoticeable oestrus of the women are all mechanisms for reducing tensions.

Didn’t the men hunt? No way. The bipedal speed was insufficient to keep up with the savannah predators. But thanks to the presence of predators such as sabre toothed tigers, there were hides all over the place, leftovers of the other carnivores of the savannah. The hides provided a new niche for the handy apes. The ANBOS could pick and scrape protein-rich tissue from the hides with the sharp edges of bones, shells and stones. And when a hide was totally clean, it made a perfect bag for carrying things, a blanket on cold nights, a screen against sun, wind, or rain, or a practical canvas for stone tools. The multipurpose hides were the ANBOS’ most valuable property. The ‘paleos’ lack attention for the importance of these hides in the technical development of our ancestors. It was the beginning of ‘the stone age’: the beginning of the use of stone flakes for processing hides.

All these environmental changes and physical adaptations developed unperceived by our ANBOS. Just like normal apes 10 million years ago, they made their daily foraging tracks in a vast territory. In the course of two million years even more open grasslands became part of their territory and daily route. All needed adaptations developed during this time. By 6 million years ago, our ANBOS were experienced savannah dwellers.

They had evolved into a new kind of chimp, a totally new species in the history of life on earth: the australopiths. The only thing which remained unchanged was their way of life. They would leave their nests early in the morning, wander along a route they knew perfectly, gathering food along the way, and finally come to the next wood where they would share the gathered food and then make their nests high in the trees. The only part of the routine that changed was that instead of eating their food while ranging on the woodlands, they carried most of the gathered food (tubers, grass seeds, larvae, eggs, and so on) to their camps to be distributed equally among group members.

99.5 % of the time we exist, our ancestors were hunter-gatherers. This is an important fact for understanding ourselves.